This program represents a multi-faceted approach to obtain basic information concerning the organisms resident in the human oral cavity, and their relationships to dental caries and periodontal diseases. It includes surveys of the bacterial flora associated with different clinical disease entities, and fundamental investigations designed to clarify the physiology and taxonomy of poorly understood groups of microorganisms. Particular emphasis is placed upon studying the ecology of suspected odontopathic bacteria. Factors affecting their attachment to oral surfaces, their transmission between subjects, and their intraoral localization are being determined. Their pathogenic potential is being assessed in experimental animal model systems, and their association with human disease is being investigated. In more applied studies, the effects of administration of certain antibiotics and other selected chemotherapeutic agents on the populations of Streptococcus mutans and other important odontopathic bacteria are being evaluated. BIBLIOGRAPHIC REFERENCES: Gibbons, R.J. 1975. Attachment of oral streptococci to mucosal surfaces. Microbiology 1975, pg 127-131. Am. Soc. Microbiol. Publ., Ed: David Schlessinger. Gibbons, R.J. and van Houte, J. 1975. Bacterial adherence in oral microbial ecology. Ann. Revs. Microbiol. 29:19-44.